Make sure you re-torque the heads until the gaskets stop compressing. See Joe Hovel's comments on why this is necessary now even though the manual doesn't say it is
I have used the search feature and have read thru numerous posts on the head gaskets. I know its recommended that I use OE Honda gaskets, but I don't really want to spend another $50-$75 on them when I have a set right in front of me. I purchased the emgo set. Inside are two head gaskets. From...
www.cx500forum.com
BTW: Welcome to the forum. Please add your location and your bike's model and model year (NOT year first registered if that's what your paperwork shows) to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).
And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and may or may not have had all of the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).
